Combination motion and acoustic piezoelectric sensor apparatus and method of use therefor

ABSTRACT

Sensors used in mapping strata beneath a marine body are described, such as used in a flexible towed array. A first sensor is a motion sensor including a conductive liquid in a chamber between a rigid tube and a piezoelectric motion film circumferentially wrapped about the tube. A second sensor is a traditional acoustic sensor or a novel acoustic sensor using a piezoelectric sensor mounted with a thin film separation layer of flexible microspheres on a rigid substrate. Additional non-acoustic sensors are optionally mounted on the rigid substrate for generation of output used to reduce noise observed by the acoustic sensors. Combinations of acoustic, non-acoustic, and motion sensors co-located in rigid streamer housing sections are provided.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of U.S. provisional patentapplication No. 61/427,775 filed Dec. 28, 2010, all of which isincorporated herein in its entirety by this reference thereto.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to use of sensors to map strata beneath abody of water and/or to sense an object in water.

DESCRIPTION OF THE RELATED ART

Towed arrays of hydrophone sensors are used to map strata beneath largebodies of water, such as gulfs, straights, and oceans.

Patents related to the current invention are summarized herein.

Streamer Cable

R. Pearce, “Non-Liquid Filled Streamer Cable with a Novel Hydrophone”,U.S. Pat. No. 5,883,857 (Mar. 16, 1999) describes a streamer cableincluding a plurality of serially coupled active cable sections havinghydrophones located within an outer jacket and a longitudinally andcentrally located electro-mechanical cable.

R. Pearce, “Non-Liquid Filled Streamer Cable with a Novel Hydrophone”,U.S. Pat. No. 6,108,267 (Aug. 22, 2000) describes a towed array having acentral strain member, an inner protective jacket about the strainmember, a foam material about the inner protective jacket, and a pottingmaterial bonded to the inner protective jacket inside an outerprotective jacket.

R. Pearce, “Method and Apparatus for a Non-Oil-Filled Towed Array with aNovel Hydrophone and Uniform Buoyancy Technique”, U.S. Pat. No.6,498,769 B1 (Dec. 24, 2002) describes a towed array having uniformbuoyancy achieved using hollow microspheres in a polyurethane matrix,where the percentage of hollow microspheres is correlated with adjacentdensity of elements of the towed array.

R. Pearce, “Acoustic Sensor Array”, U.S. Pat. No. 6,614,723 B2 (Sep. 2,2003) describes an acoustic sensor array having buoyant sections formedusing reaction injection molding with controlled and varying amounts ofhollow microspheres and polyurethane as a function of position on thearray.

Sensor

R. Pearce, “Acoustic Transducer”, U.S. Pat. No. 5,357,486 (Oct. 18,1994) describes a piezoelectric film strip wrapped around a mandrelhaving stand off collars on each end. Variations in hydrodynamicpressure flex the film strip in tension to generate a voltage.

R. Pearce, “Acoustic Sensor”, U.S. Pat. No. 5,361,240 (Nov. 1, 1994)describes an acoustic sensor having a hollow mandrel with an outersurface defining a concavity and a flexible piezoelectric film wrappedabout the outer surface forming a volume between the film and themandrel, the volume serving as a pressure compensating chamber.

R. Pearce, “Acoustic Sensor and Array Thereof”, U.S. Pat. No. 5,774,423(Jun. 30, 1998) describes an acoustic sensor having electrically coupledpiezoelectric materials.

R. Pearce, “Acoustic Sensor and Array Thereof”, U.S. Pat. No. 5,982,708(Nov. 9, 1999) describes an acoustic sensor having a substrate with aconcavity on an outer surface that is sealingly enclosed by an activemember of a piezoelectric material.

R. Pearce, “Acoustic Sensor and Array Thereof”, U.S. Pat. No. 6,108,274(Aug. 22, 2000) describes an acoustic sensor having a mandrel, a firstsubstrate on an outer surface of the mandrel, a damping layer betweenthe first substrate and a second substrate, a piezoelectric sensormounted to the second substrate, and an encapsulating material on thepiezoelectric material.

R. Pearce, “Method and Apparatus for a Non-Oil-Filled Towed Array with aNovel Hydrophone and Uniform Buoyancy Technique”, U.S. Pat. No.6,819,631 B2 (Nov. 16, 2004) describes a towable hydrophone having adiaphragm with a tubular shape, a thin film piezoelectric elementattached to the diaphragm, the diaphragm having a back plane having acylindrical shape, and at least one longitudinal rib on the exterior ofthe back plane, where the back plane and exterior rib slidingly engagethe tubular diaphragm.

Problem Statement

What is needed is one or more sensors for use in mapping strata under awater body having increased insensitivity to noise sources and enhancedband width.

SUMMARY OF THE INVENTION

The invention comprises a piezoelectric sensor method and apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention is derived byreferring to the detailed description and claims when considered inconnection with the Figures, wherein like reference numbers refer tosimilar items throughout the Figures.

FIG. 1 illustrates a towed sensor array and potential water body surfaceinterference;

FIG. 2A illustrates motion sensor elements in a towable accelerometersensor.

FIG. 2B illustrates a vertical cross-section of a towable accelerometersensor.

FIG. 3A illustrates an acoustic sensor using microspheres.

FIG. 3B illustrates a cross-section of an acoustic sensor usingmicrospheres.

FIG. 4 illustrates stacked sensors; and

FIG. 5 illustrates a combined acoustic/motion sensor.

Elements and steps in the figures are illustrated for simplicity andclarity and have not necessarily been rendered according to anyparticular sequence. For example, steps that are performed concurrentlyor in different order are illustrated in the figures to help improveunderstanding of embodiments of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention comprises a noise cancelling piezoelectric sensorapparatus and method of use thereof.

In one embodiment, a liquid metal electrode coupled with a piezoelectricelement is used to sense upward vertical motion while minimizingdownward vertical motion.

In another embodiment, an acoustic sensor is provided having apiezoelectric sensor coupled with a microsphere loaded transfer adhesiveas a compressible gas chamber.

In still yet another embodiment, an acoustic sensor is verticallycoupled with a motion sensor to form a dual output seismic surveysensor. For example, a method and apparatus is described for amonolithic dual output, piezoelectric polymer thin film flexiblemicrosphere backed flow noise cancelling acoustic sensor. The sensoroptionally uses a conductive liquid piezoelectric polymer thin filmmotion sensor embodied in a flexible syntactic elastomer based solidseismic streamer for enhanced data acquisition in marine seismic surveysand passive acquisition.

In one example, the system includes two piezopolymer thin film elementsconfigured in such a manner as to form a dedicated motion sensor and adedicated flow noise cancelling acoustic sensor, both of which areexcited by forces and/or identical forces manifested as dynamic pressurewith immunity to acceleration and dynamic particle motion with immunityto dynamic pressure so as to allow for the discreet measurement ofacoustic energy and particle motion present at a single location. Theacoustic sensor being embodied in such a manner as to allow the inherentresponse characteristics of thin film polyvinylidene fluoride (PVDF) tosense both acoustics and noise produced by the turbulent boundary layeras dynamic pressure while simultaneously sensing only the turbulentboundary layer manifested as a response to a force, producing a responsein the non-acoustic portion of the element to the turbulent boundarylayer that is about one hundred eighty degrees out of phase with thatdetected on the acoustic portion of the element. This is optionallyaccomplished in a single contiguous sensor mechanically constrained insuch a way as to allow a portion of the element to respond to dynamicpressure and a portion of the element to respond only to mechanicalforce. A simple embodiment of this invention is presented with thesensor comprised of a single piece of PVDF film where a single strip ofacoustic sensor is surrounded by two strips of force sensor. Complexpatterns are also available to enhance the performance of the inventionutilizing fractal pattern sampling of the turbulent boundary layer. Thecompleted sensors are then used to construct a seismic streamer sectionnecessarily of a solid construction where the sensors are placed.

Axes

Referring now to FIG. 1, herein an x-axis is in a horizontal directionof towing of a sensor array. The x/y axes form a plane parallel to awater body surface. The z-axis is aligned with gravity. Typically, thethickness of a piezoelectric film is viewed in terms of a z-axis, thoughthe piezoelectric film is optionally rolled about a mandrel, describedinfra.

Piezoelectric Material

Piezoelectricity is charge that accumulates in certain solid materialsin response to applied mechanical stress. A piezoelectric materialgenerates electricity from applied pressure.

An example of a piezoelectric material is polyvinylidene fluoride(PVDF). Unlike ceramics, where the crystal structure of the materialcreates the piezoelectric effect, in the PVDF polymer intertwinedlong-chain molecules attract and repel each other when an electric fieldis applied.

The polyvinylidene material is particularly useful in aqueousenvironments as the acoustic impedance of PVDF is similar to that ofwater. An external mechanical force applied to a film of polyvinylidenefluoride results in a compressive or tensile force strain. A film ofPVDF develops an open circuit voltage, or electrical charge, which isproportional to the changes in the mechanical stress or strain. Byconvention, the polarization axis is the thickness axis of thepolyvinylidene material. Tensile stress may take place along either thelongitudinal axis or the width axis.

Herein, for clarity, polyvinylidene fluoride is used as an example ofthe piezoelectric material. However, any material that generates acharge in response to pressure is optionally used. Examples include:man-made crystals, such as gallium orthophosphate, a quartz analogiccrystal, and langasite; man-made ceramics, such as a titanate, aniobate, a tantalate, or a tungstate; and/or a lead-free piezoceramic.

A PVDF material is characterized in terms of a strip of PVDF film. ThePVDF film includes a width axis or x-x axis, a length axis or y-y axis,and a thickness axis or z-z axis. The PVDF film x-x axis is lesssensitive, in terms of developed charge, to applied forces than thelength axis or the thickness axis of the PVDF film. Hence, in thesensors described herein, the width axis of the PVDF film is typicallyabout parallel to the towing direction of the sensor array to minimizenoise signals resultant from towing of the sensor array with a cableunder varying strain. As described, infra, expansion of the y-y axis ofthe PVDF film is optionally restrained in a mounting step, which resultsin increased thickness changes of the PVDF film resultant from appliedforces. The increased thickness change as a function of applied force isequivalent to an increased signal-to-noise ratio.

The PVDF film is optionally cut, shaped, or wrapped about a surface,such as a mandrel or hollow tube.

A PVDF sensor is a PVDF film coupled with at least one charge transferelement, such as a conductive wire. In one case, a PVDF sensor includesa PVDF film coated on both sides with a conductive ink. In a secondcase, the PVDF film is coated on one side with a conductive ink and theopposite side makes contact with a conductive fluid, as described infra,to form a PVDF sensor.

Conditioning Electronics

Electric output from the PVDF sensor is carried along a conductiveelement, such as a wire, to an electrical circuit. The electricalcircuit optionally includes: a current to voltage converter, such as apreamplifier, an amplifier, processing electronics, an analog-to-digitalconverter, and/or a data buss. Signal from a first PVDF sensor isoptionally:

-   -   combined with signal from a second PVDF sensor using the        on-board electrical circuit; and/or    -   is post processed after communication of the gathered signal to        a processing center.        Towed Sensor Array

Still referring to FIG. 1, a system for mapping strata 100 under a floorof a water body is illustrated. In the illustrated example, a ship 110tows one or more sensor arrays 120. A sensor array 120 includes at leasta streamer cable 122 and a sensor 124.

The streamer cable 122 includes:

-   -   a strain member, such as a central strain member;    -   a wire bundle configured to carry power and/or data, the wire        bundle is preferably wrapped about the strain member to reduce        strain from towing;    -   a plurality of sensors 124, such as about equispaced or not        equally spaced hydrophones, non-acoustic sensors, and/or        accelerometers;    -   electronics;    -   a buoyancy element; and/or    -   a protective jacket about the sensors, strain member, and wire        bundle.

The sensors are further described, infra.

In use, a seismic shock wave is generated, such as with an explosive130. For clarity of presentation, a single shock wave 140 from theexplosive 130 is illustrated. The shock wave 140 partially reflects froma floor 150 of the water body, and/or from a series of strata layers152, 154 under the water body floor 150. Again for clarity, only asubset of the surface and strata reflections are illustrated. In onecase, the surface reflections yield a vertically rising seismic wave 142that strikes the one or more sensors 124. In a second case, a seismicwave at least partially reflects off of a water body surface 160 toyield a vertically descending seismic wave 144, which strikes the one ormore sensors 124. The vertically descending seismic wave is aninterference signal, which reduces the bandwidth and associatedsignal-to-noise ratio of the sensors 124.

Still referring to FIG. 1, those skilled in the art know that a matrixof sensors may be used to map strata layers, where the matrix of sensorseach detect a plurality of seismic waves, each of the seismic wavesreflected off of a plurality of strata layers at a plurality of spatialpositions as a function of time.

Sensors

The sensors 124 are further described. Any of the sensors 124 describedherein are optionally coated with a flexible solid material as part ofthe streamer 122. Further, sensors 124 are optionally positioned at anyx-axis position of the streamer 122 to form the sensor array 120, thoughequispacing of like sensor elements 124 is preferred.

Motion Sensor

Referring now to FIG. 2A and FIG. 2B, an example of a motion sensor 200or accelerometer is described. For clarity, elements of the motionsensor 200 are illustrated in a rolled out plane in FIG. 2A, while thesame elements of the motion sensor are illustrated wrapped about asubstrate 210 in FIG. 2B.

Still referring to FIG. 2A, the motion sensor 200 includes:

-   -   a substrate 210;    -   a piezoelectric motion film 220 optionally attached to a        diaphragm; and    -   a hollow cavity, hollow chamber, and/or an enclosed chamber 230        between the substrate 210 and the piezoelectric motion film 220.

Each of the motion sensor 200 elements are further described herein.

In practice, the substrate 210 is optionally a hollow tube or a hollowmandrel. The substrate 210 is sufficiently rigid to isolate internallyradiated stresses from the embodied piezo elements in both the motionsensor 200 and the acoustic sensor 300 described, infra. The substrate210 optionally includes a concave inner surface, defining an inner wallof a tube. The tube is optionally used to contain and/or to constrainmovement of centrally placed elements, such as a strain member of thestreamer cable 122, the wire bundle configured to carry power and/ordata, a shock absorbing element, and/or the electronics. The substrate210 also optionally includes a convex outer surface upon which thesensor elements are mounted. The convex outer surface of the substrate210 optionally contains an outer concavity or channel 211. The channelor cavity 211 is created either through machining or through a moldingprocess by which the channel 211 is presented around a circumferencelocated outside the rigid mandrel or substrate 210. Sensor elements areoptionally located in the outer concavity or channel 211. For example,in one case the substrate 210 includes a pair of inner shoulders 212,which function as a mechanical support for a diaphragm and/or thepiezoelectric motion film 220. The inner shoulders 212 are eithermachined or molded and are located outside and to the side of thecreated channel 211 at a depth and width sufficient to allow attachmentof the piezofilm motion sensor element 220 forming a sealed chamber 230.Optionally, the motion sensor 200 includes an outer motion sensorhousing 240. The outer motion sensor housing 240 or second rigidcylindrical mandrel is positioned over a cavity formed by the outershoulders 214 thus sealing the entire conductive fluid filledaccelerometer sensor or motion sensor 200 inside. The outer motionsensor housing 240 prevents or reduces the motion sensor 200 fromresponding to dynamic pressure. Further, the outer motion sensor housing240 optionally forms an outer mandrel upon which an outer passive flownoise cancelling acoustic sensor 300 is positioned. Preferably, theouter motion sensor housing 240 is rigid or semi-rigid. The outer motionsensor housing 240 is optionally connected to the substrate 210, such asthrough a pair of outer shoulders 214 positioned along the x-axisfurther from a center of the enclosed chamber 230 relative to the innershoulders 212. The additional set of outer shoulders 214 adjacent andoutside the inner shoulders 212 optionally form a second chamber abovethe first thin film piezoelectric element. Both the inner and outershoulders 212, 214 are optionally a part the substrate 210, areremovable elements affixed to the substrate 210, are affixed to themotion sensor housing 240, and/or are part of the motion sensor housing240.

The piezoelectric motion film 220 is mounted radially outward from thesubstrate 210 in a manner forming a sealed hollow chamber 230therebetween. For example, the piezoelectric polymer thin motion filmelement 220 is constructed with a deposited single electrode on theouter surface 221 so as to create a continuous electrode around thecircumference of the resulting piezofilm cylinder created when the filmis attached to the shoulders 212 previously described and sealed wherethe film wrap overlaps creating the hollow and sealed chamber 230between the piezoelectric motion film 220 and the substrate 210 withinthe channel 211. For example, the piezoelectric motion film 220 ismounted over a portion of the outer concavity or channel of thesubstrate 210 or is mounted directly or indirectly to the innershoulders 212. The piezoelectric motion film 220 optionally forms one ormore layers circumferentially surrounding the substrate 210. The hollowchamber 230 extends to at least partially circumferentially encompass anx-axis section of the substrate 210. In one case, the piezoelectric filmmounts directly to the substrate 210, such as by mounting to the innershoulders 212 of the substrate 210. Mechanically affixing, such as witha wrap and/or an adhesive, the piezoelectric motion film 220 to theinner shoulders 212 restricts movement of the y-y axis of thepiezoelectric film. The restricted y-y axis motion of the piezoelectricmotion film 220 and the orientation of the x-x axis of the piezoelectricfilm along the x-axis or towing axis results in enhanced changes in thez-z thickness axis of the piezoelectric film as a response topressure/size changes resultant from the seismic waves 140, whichincreases the signal-to-noise ratio of the motion sensor 200. Inadditional cases, the piezoelectric motion film 220 is indirectlyaffixed to the substrate 210, such as through the use of a diaphragm. Inall cases, at least a portion of the hollow chamber 230 is physicallypositioned between the substrate 210 and the piezoelectric motion film220.

Changes in thickness of the piezoelectric motion film 220, which isproportional to the changes in the mechanical stress or strain resultingfrom the seismic wave 140, is measured using electrical connections tothe piezoelectric motion film 220. A first electrical connection is madeto an outer surface 221 or radially outward surface of the piezoelectricmotion film 220 using conductive material, such as a flexible conductiveink 222, applied to the outer surface 221 of the piezoelectric film. Forexample, a wire is attached by suitable means to the plated outerelectrode or conductive ink 222 of the piezoelectric motion film 220 andpassed through the outer shoulders 214, where the wire is connected tosignal wires of the motion sensor 200. A second electrical connection toat least a portion of a radially inner surface 223 of the piezoelectricmotion film 220 is made using a conductive fluid 232, contained in thehollow chamber 230, where the conductive fluid contacts the radiallyinner surface 223 of the piezoelectric motion film 220. At least oneelectrical lead 228 runs through a portion of the conductive fluid 232in the hollow chamber 230. The open circuit voltage, or electricalcharge, of the piezoelectric acoustic film 220, which is proportional tothe changes in the mechanical stress or strain, is measured using theelectrical signal carried by the conductive ink 222 and the electricallead 228. For example, the electrical lead is an electrically conductivewire or sheet adhered to the outer diameter of the hollow chamber 230 soas to form a conductive surface or electrode using a stable metallicmaterial. In a case where wire is used, the wire is optionally wrapped aplurality of turns around the circumference of the substrate 210 so asto create a continuous conductive path around the circumference passingthe wire from the inside of the conductive fluid 232 filled hollowchamber 230 to the outside of the hollow chamber 230 through a hole inthe inner shoulder 211, which is later sealed to prevent leakage of theconductive fluid. As the external hydrostatic pressure increases ordecreases, resultant from the seismic wave 140, contraction or expansionof the substrate 210 and/or diaphragm to which the substrate isoptionally mounted results in corresponding contraction or expansion ofthe hollow chamber 230, the conductive fluid 232 in hollow chamber 230,the diaphragm, and/or the piezoelectric motion film 220. Changes in thepiezoelectric motion film 220, such as in the z-z thickness axis, aremeasured using the first electrical connection made to the conductiveink 222 on one side of the piezoelectric motion film 220 and the secondelectrical connection using the electrical lead 228 passing through theconductive fluid 232 on the opposite side of the piezoelectric film.

The conductive fluid 232 has a density greater than air, which causesthe conductive fluid 232 to settle to the bottom of the hollow chamber230. In practice, the hollow chamber has a capacity volume and thefilling volume of the conductive fluid 232 is less than the capacityvolume, such as less than about 75, 50, 40, 30, or 20 percent of thecapacity volume. As the conductive fluid 232 is used to transmit theseismic wave 140 and the conductive fluid only fills a lower portion ofthe hollow chamber 230, the vertically ascending seismic waves 142 aresensed by the motion sensor 200 and the vertically descending seismicwaves 144 are dampened and/or are not detected by the motion sensor 200.As the motion sensor 200 is insensitive or less sensitive to thevertically descending seismic waves 144, the reflected signal from thewater body surface 160 is not detected and the useable bandwidth orsignal-to-noise ratio of the motion sensor is enhanced relative to amotion sensor not having a hollow chamber partially filled with aconductive fluid.

Generally, a sufficient amount of a preferably non-toxic conductivefluid 232 is introduced into the hollow chamber 230 or sealed cavity toform a liquid electrode positioned by gravity at the lowest point in thecircumference of the hollow chamber 230 or inner chamber. The fluid 232resides in contact with the inside diameter of the wrapped piezoelectricmotion polymer film 220, spreading over an about fixed surface areadefined by the amount of the conductive fluid 232 placed in the hollowchamber 230. The amount of the conductive fluid 232 determines thereactive mass as well as the electrical characteristics of thepiezoelectric sensor in terms of capacitance. The material comes incontact with the piezoelectric motion film 220 and simultaneously incontact with the conductive wire 228 wrapped around the circumference ofthe inner diameter of the cavity or channel 211 thus transferring signalfrom the piezoelectric motion film 220 inner surface 223, through theconductive fluid 232 or liquid metal, through the conductive wire wrap228 and out of the hollow chamber 230 to the outside of the channel 211or cavity where it is connected to signal wires of the motion sensor200.

Examples of a conductive fluid 232 include at least one of:

-   -   a fluid capable of electrical conductance;    -   a non-aqueous fluid;    -   a fluid containing a metal;    -   a fluid having a freezing point less than zero degrees        centigrade;    -   a fluid having a freezing point of negative two degrees        centigrade or less;    -   a fluid having an electrical conductivity of at least 2,000,        5,000, and/or 10,000 siemens per meter (S/m) at 20° C.;    -   a eutectic alloy;    -   a fluid including at least five percent tin;    -   a fluid containing at least five percent gallium;    -   a fluid containing at least five percent indium; and    -   a galinstan® (Geratherm Medical AG, Germany) fluid.

In practice, the conductive fluid 232 moves in the hollow chamber 230due to motion of the streamer cable 122. As the conductive fluid sloshesor flows along the y/z axis in the hollow chamber 230 about thesubstrate 210, the contact area of the conductive fluid 232 with theinner surface 223 of the piezoelectric motion film 220 is aboutconstant. Hence, the motion sensor 200 is generally unaffected by motionof the conductive fluid 232. However, optionally a motion damping fluid234 is added to the hollow chamber 230. The damping fluid 234 in thehollow chamber 230 or cavity prevents wetting of the surfaces by theconductive fluid and/or provides damping of the movement of the fluidunder cross-axis excitation, thus limiting response to undesirable offaxis motion preserving the uniaxial response of the motion sensor. Themotion damping fluid 234 is substantially non-conductive, is aboutnon-miscible with the conductive fluid 232, and/or has a density lessthan that of the conductive fluid 232. Optionally, the volume of themotion damping fluid 234 and the volume of conductive fluid 232 combineto about equal the capacity volume of the hollow chamber 230. Thephysical resistance of the motion damping fluid 234 reduces movement ofthe conductive fluid along the y/z axis in the hollow chamber 230 aboutthe substrate 210.

In any of the sensors 124 described herein, any of the layers, such asan outer buoyancy element are optionally configured with glass spheres,which function as a buoyancy element. Generally, the glass spheres areincompressible up to about two thousand pounds per square inch. Glassspheres are useful in maintenance of uniform buoyancy regardless of thedepth at which the streamer 120 is towed. A preferred glass sphere has adensity of about 0.32 g/cm³; however the glass spheres optionally have adensity of less than water and/or less than about 0.9, 0.8, 0.7, 0.6,0.5, 0.4, 0.3, or 0.2 g/cm³.

Acoustic Sensor

Referring now to FIG. 3A and FIG. 3B, an acoustic sensor 300 isillustrated. The acoustic sensor uses a piezoelectric film, which isdescribed herein as a piezoelectric acoustic film 330 to distinguishfrom the above described piezoelectric motion film 220, though bothmaintain the general properties of a piezoelectric material or element.

Still referring to FIG. 3A and FIG. 3B, in this example the acousticsensor 300 uses a mandrel 310. However, the mandrel 310 is optionallyany rigid surface, such as a hollow cylinder or tube about the motionsensor 200 described supra. For example, the outer motion sensor housing240 of the motion sensor 200 is optionally used in place of the mandrel310. A piezoelectric acoustic film 330 is wrapped about the mandrel 310.The piezoelectric acoustic film 330 includes a conductive material onboth the outer surface 332 and the inner surface 336. For example, afirst electrical connector 334 is connected to a first flexibleconductive ink circuit on the outer surface 332 of the piezoelectricacoustic film 330. Similarly, a second electrical connector 338 isconnected to a second flexible conductive ink circuit on the innersurface 336 of the piezoelectric acoustic film 330. A set of flexiblemicrospheres 320 are positioned between the mandrel 310 and the innerlayer 336 of the piezoelectric acoustic film 330. The outer surface 332of the piezoelectric acoustic film 330 is optionally coated or containedwithin a flexible solid 340.

The microspheres 320 are responsive to pressure and mechanically isolatethe piezoelectric acoustic film 330. For example, if the acoustic sensor300 is mounted on a structure that is struck, the microspheres 320isolate the piezoelectric acoustic film 330 of the acoustic sensor 300from the transmitted energy in the structure.

The set of microspheres 320 is optionally a single layer of microspheresor a thickness of microspheres 320, such as less than about 10, 20, 30,40, 50, 60, 70, 80, 90, 100, 150, 200, 300, 500, 1000, 5000, or 10,000micrometers thickness. The average diameter of the microspheres 320 isless than about 1, 2, 5, 10, 20, 50, 100, or 1000 micrometers.

The microspheres 320 are generally flexible, are preferably plastic, andare not to be confused with incompressible glass spheres used forbuoyancy control, such as in the outer member.

The microspheres 320 in the hydrophone sensor 300 are optionallyflexible and/or plastic. In the piezoelectric acoustic sensor 300 orhydrophone, the compressible microspheres 320 are optionally placed intoand/or onto an adhesive material, such as to form an adhesive strip or asphere coated and/or impregnated transfer adhesive. For example, thetransfer adhesive is optionally a flexible layer, polymer, or tapecoated on preferably one side and optionally both sides with a layer ofthe flexible microspheres 320. The flexible microspheres on and/or inthe transfer adhesive are wrapped about the rigid surface or mandrel, orrigid motion sensor housing 240. Preferably, the microspheres 320 arecoated onto a surface of the transfer adhesive and the sphere coatedsurface of the transfer adhesive is wrapped about the rigid motionsensor housing 240 to form a layer of flexible microspheres 320 on theinner surface of the piezoelectric polymer acoustic film 330circumferentially wrapped on the rigid substrate 240 or mandrel 310.

In practice, an acoustic pressure wave 140 is converted to a mechanicalmotion at the water/flexible solid 340 interface. The mechanical motionis transferred to the piezoelectric acoustic film 330, where a change inshape of the piezoelectric acoustic film 330 is picked up as acorresponding electrical signal using the first electrical connectorconnected to the first flexible conductive ink circuit on the outersurface 332 of the piezoelectric acoustic film 330 and the secondflexible conductive ink circuit on the inner surface 336 of thepiezoelectric acoustic film 330. The electrical signal is amplified andprocessed, as described supra, to yield information on the floor 150 ofthe water body and on the series of strata layers 152, 154 under thewater body floor 150.

Multiple Sensors

Multiple sensors are optionally used in each sensor section of thesensor array 120. For example, output from one or more motion sensor 200is combined with output from one or more acoustic sensor 300, and/oroutput from a first motion sensor is combined with output from a secondmotion sensor, output from a first acoustic sensor is combined withoutput from a second acoustic sensor. The process of combining thesignals optionally occurs in a pre-processing stage by use of electroniccircuitry and/or occurs in a post-processing digital signal processingprocess.

Optionally, the central elements, such as any of the sensor elementsdescribed herein, are encased in an outer element, such as a buoyancyelement. The buoyancy element:

-   -   is optionally used with any sensor 124 herein;    -   optionally contains non-compressible glass spheres; and    -   contains varying amounts of the glass spheres to adjust buoyancy        as a function of x-axis position and/or as a function of        streamer element size and density.        Stacked Sensors

Optionally, two or more sensors are stacked along the y- and z-axes at agiven point or length along the x-axis of the streamer cable 122.

Referring now to FIG. 4, an example of a motion sensor and an acousticsensor in a stacked geometry 400 is illustrated. For clarity, a radialcross-section of only one side of the sensor is illustrated. Generally,the stacked motion sensor 410 includes any of the elements of the motionsensor 200. Similarly, the stacked acoustic sensor 470 includes any ofthe elements of the acoustic sensor 300.

Still referring to FIG. 4, for clarity of presentation characterreference labels for like elements of the motion sensor 200 and theacoustic sensor 300 are used in the stacked sensor 400. However, varyingmounting structures, connections, and orientations of elements are usedto further illustrate permutations and combinations of sensor 124elements.

Still referring to FIG. 4, an example of a combined sensor is provided.While individual sensor sections are optionally placed in differentpositions relative to each other, the illustrated example uses:

-   -   a sensor accelerometer 410 positioned on a substrate 210;    -   an optional first non-acoustic sensor 430 positioned radially        outward from a center of the substrate 210 relative to the        sensor accelerometer 410;    -   an optional second non-acoustic sensor 450 positioned radially        outward from a center of the substrate 210 relative to the        sensor accelerometer 410; and    -   an acoustic sensor 470 positioned both radially outward from the        center of the substrate 210 relative to the sensor accelerometer        410 and about adjacent to at least one of the first and second        non-acoustic sensors 430, 450.

Generally, the sensor accelerometer 410 uses piezoelectric motion film220 between a metalized ink 222 conductor on a first z-axis side, aconductive fluid 232 in an enclosed chamber 230 on a second z-axis sideof the piezoelectric motion film 220, and an electrical lead 228 passingthrough a portion of the conductive fluid 232 in the hollow chamber 230.Any of the motion sensor 200 elements described supra, such as the innershoulders 212, diaphragm, and/or the edge constraints are optionallyused. Optionally, the accelerometer 410 in the combined sensor 400 doesnot use the conductive fluid 432 and instead uses a traditional motionsensor design.

Generally, the non-acoustic sensors 430, 450 are offset from thesubstrate 210 using a rigid support, such as the outer shoulders 214.The non-acoustic sensors are attached without a substantial gap in rigidlayers to the convex side of the substrate 210, such as through theouter shoulder 214 and or through the rigid motion sensor housing 240circumferentially encompassing the sensor accelerometer 410. The one ormore optional non-acoustic sensors 430, 450 are preferably locatedwithin about 1, 2, 3, 4, 5, 10, 15, or 20 centimeters of the sensoraccelerometer 410 and/or the acoustic sensor 470. Each of the one ormore non-acoustic sensors 430, 450 include a piezoelectric film betweentwo conductive layers, such as metalized ink layers.

Generally, the offset acoustic sensor 470 uses any of the elements ofthe acoustic sensor 300. The offset acoustic sensor 470 includes apiezoelectric acoustic film 330 between conductive material on both theouter surface 332 and the inner surface 336, as described supra. A setof flexible microspheres 320 or a pressure equalizing hollow cavity arepositioned between the motion sensor housing 240 and the inner layer 336of the piezoelectric acoustic film 330. The outer surface 332 of thepiezoelectric acoustic film 330 is optionally coated with a flexiblesolid 490 and/or a buoyancy element.

Generally, the sensor accelerometer 410, non-acoustic sensor 450, andoffset acoustic sensor 470 are optionally positioned in any spatialposition relative to each other. For example:

-   -   the offset acoustic sensor 470 is optionally positioned radially        outward from the non-acoustic sensor 450;    -   the non-acoustic sensor 450 is optionally at a first radial        distance away from the streamer cable 122 that is different than        one or both of a second radial distance between the streamer        cable 122 and the acoustic sensor 470 or a third radial distance        between the streamer cable and the sensor accelerometer 410;        and/or    -   the sensor accelerometer 410, non-acoustic sensor 450, and        offset acoustic sensor 470 are vertically stacked.

Stacking of at least two of the sensor accelerometer 410, thenon-acoustic sensor 450, and the offset acoustic sensor 470 reduces thestiff length 480 section(s) of the sensor array 120, which aids indurability and deployment of the sensor array 120.

EXAMPLE I

Referring now to FIG. 5, another example of a motion sensor and anacoustic sensor in a stacked geometry 500 is illustrated. Particulardescriptions of elements provided herein optionally apply to any of thesensors described, supra, and vise-versa.

Still referring to FIG. 5, the present example describes a novelmonolithic dual output, acoustic and particle motion sensor for use in aflexible syntactic elastomer based solid seismic streamer for marineseismic surveys where the acoustic sensor 300 incorporates a novel lowcost method of production and provides the ability to passively detectand cancel unwanted noise due to flow using a liquid metal motion sensor200 detecting particle motion, allowing for the combination of theresulting outputs to improve signal-to-noise ratio and recover lostbandwidth due to the interference of surface reflected energy in marineseismic surveys.

Still referring to FIG. 5, the thin film piezoelectric acoustic sensor300 optionally uses a flexible microsphere 322 loaded adhesive transfermaterial, which is applied to one side of the plated film along a lengthfrom the end equal to the circumference of the outer mandrel 240.Optionally, the length of the microsphere 322 loaded adhesive material,as part of the piezoelectric acoustic sensor 300, is positioned betweentwo adjacent strips of non-sphere loaded adhesive forming non-acousticsensors, as described infra. The non-sphere loaded adhesive stripcontinues over the remaining length of the piezofilm. Beginning with theend of the piezopolymer film that is coated with the flexiblemicrosphere loaded transfer adhesive, the film is attached directly tothe rigid mandrel and wrapped around the circumference of the mandrel240 a minimum of one single wrap or a plurality of wraps depending onthe length of the piezoelectric film.

A means of connecting the electrodes of the film is provided to whichwires are attached to a means by which the signal can be passed throughthe outer shoulders of the assembly.

Rigid stress isolating blockers specifically designed to allow for theinner molding and attachment of the embodied sensors to the primaryelectromechanical cable are then molded to the ends of the innermostmandrel with conductive pins insert molded to allow for the passing ofthe dual sensor's respective outputs through the outer shoulders to theadjacent sensors and ultimately passing the signals to the core of theelectromechanical cable. The shapes at the ends of the shoulder moldingsare specifically configured to prevent the entrapment of air bubbles inthe vertical inner molding process.

Each individual sensor embodiment is then over molded between thepreviously molded shoulders resident at the ends of the individualinnermost mandrels to form a smooth shape suitable for secondary overmolding with an elastomeric flexible syntactic flotation material.

Streamer Cable

Completed sensor pairs are then arranged into a group of sensors thatforms the acoustic and motion sensor apertures of the seismic streamersection.

The acoustic sensors 300 are typically combined electrically in parallelby use of a twisted pair of conductors connected from one sensor to thenext with sufficient length so as to allow for the helix of the wirearound the core cable between sensors to prevent breakage when thestreamer is bent either in handling or in winding on a reel.

The motion sensors 200 are typically combined electrically in parallelby use of a second twisted pair of conductors connected from one sensorto the next with sufficient length so as to allow for the helix of thewire between sensors to prevent breakage when the streamer is benteither in handling or in winding on a reel.

The completed inner and outer molded sensor section is then over moldedwith a second form of glass spheres or glass microspheres loaded into anincompressible elastomeric flotation compound that creates a uniformdiameter continuous flexible sensor section.

Still referring to FIG. 5, optional and exemplary relationships betweensensor 124 components are further described:

-   -   The rigid mandrel or substrate 210 forms the base of the sensor        construction.    -   Features molded over the rigid substrate 210, such as the inner        shoulders 212 and outer shoulders 214 form the necessary        cavities and supporting structures to place the components of        the dual sensors.    -   The polymer film motion sensor element 220 resides between the        inner shoulders 212 and forms the cavity or hollow chamber 230        into which the liquid metal electrode 232 is placed.    -   The motion sensor 200 shoulders 212 reside beneath or adjacent        to the acoustic sensor 300 shoulders 214.    -   The conductive material 228 placed around the inner base of the        cavity resides in contact with the liquid metal 232.    -   The second set of shoulders 214 provides for the mounting of a        second rigid tube 240, which forms a cylindrical cavity 239        around the motion sensor element.    -   The second rigid tube 240 forms the substrate for the acoustic        sensor 300 element, which resides outside the circumference of        the second rigid tube.    -   The second piezo-element 330 with it's patterned syntactic        loaded adhesive is then wrapped around the outer rigid substrate        240 and forms the passive flow noise cancelling acoustic sensor        300.    -   The electrical wires from each respective sensor are attached        together either in parallel or series to create a group of        sensors that comprise a discreet channel within the seismic        streamer 122.    -   The group of sensors are placed on the core cable by sliding the        cable through the inner diameter of the sensor embodiment.    -   Acoustic output from the acoustic sensor 300 is wired separate        and apart from acceleration output from the acceleration sensor        200 and both sensors are presented to an opening in the inner        electromechanical cable where they are attached to their        respective pairs of wires within the core cable.    -   The discreet sensor embodiments are placed in a mold that        presents the individual sensor embodiments to their desired        locations within the group.    -   The group of sensors is then molded to the inner core cable with        the novel shoulder shape of the individual embodiments        preventing the entrapment of air bubbles during the molding        process.    -   The cable is terminated with connectors located at each end.        Each cable length comprises a section of the cable.    -   Each section of the cable is then presented to the process of        over molding of the syntactic flotation material which completes        the process of construction of the dual sensor seismic section        with passive flow noise cancelling.

Still referring to FIG. 5, a description of how components work togetheris provided:

-   -   The first inner rigid substrate 210 provides a rigid form that        isolates mechanical energy present in the core electromechanical        cable from both the motion sensor 200 and the passive flow noise        cancelling acoustic sensor 300.    -   The inner rigid substrate 210 provides a rigid form upon which        mechanical features are molded. The substrate is preferably a        rigid filled plastic for ease of manufacture that form the        embodiment and form for both the motion 200 and flow noise        cancelling acoustic sensor 300 and the later molded rigid stress        isolating, bubble eliminating outer shoulders.    -   A piezoelectric polymer film element 220 is constructed where a        single side 221 of the film 220 receives a conductive coating        222 forming an electrode plate and wrapped about the shoulders        present at the edge of the molded cavity that reside about the        circumference of the molded form forming a sealed cavity about        the circumference and between the outer diameter of the inner        molded form and the inner diameter of the wrapped piezoelectric        element where the metalized electrode resides on the outer        diameter of the piezoelectric film.    -   A conductive element 228 is wrapped a plurality of wraps about        the outer diameter of the inner molded form 210 to create an        inner electrode conductive surface with one end presented        through and outside the sealed chamber available to attach a        conductor for signal transmission.    -   An amount of a conductive liquid metal 232 is introduced into        the volume 230 residing between the inner wrapped conductor 228        and the non-metalized inner diameter of the piezoelectric film        220 forming the second electrode of the piezopolymer        transducers.    -   The liquid metal 232 functions as both the electrode for the        piezopolymer film as well as the deforming mass of the resulting        motion sensor.    -   The liquid metal 232 consistently resides at the lowest        gravitational point in the chamber regardless of the radial        orientation of the entire embodiment.    -   Vertical motion of the entire sensor results in the acceleration        of the liquid mass 232, which deforms the area of the        piezoelectric polymer film 220, changing the length of the d31        axis and d32 axis in the area in which the liquid metal 232        resides.    -   Those areas in which no liquid metal 232 resides do not        contribute to the output of the motion sensor 200. Motion that        is not in the vertical plane tends also not to create an output        from the piezoelectric polymer sensor 200 with only vertical        motion creating an output proportional to the change in velocity        of the motion.    -   The motion sensor 200 is enclosed in a rigid tube 240, which        prevents acoustic energy from contributing to the output of the        piezoelectric motion sensor 200.    -   The second tube 240 forms the mandrel upon which the acoustic        element is constructed and isolates the acoustic sensor 300 from        mechanical energy present in the core electro mechanical cable.    -   A second piezoelectric polymer element 330 is constructed and        plated on both sides to create a piezoelectric element. The thin        film piezoacoustic sensor 300 is created using a novel flexible        microsphere loaded adhesive transfer material, which covers a        specific area on one side of the plated film 330 along a length        from the end equal to the circumference of the outer mandrel 240        and positioned between two adjacent strips of non-sphere loaded        transfer adhesive 430, 450. Regions of the adhesive strip that        are not coated with spheres continue over and above the        remaining length of the piezo film. Beginning at the end of the        piezopolymer film that is coated with the flexible microsphere        loaded transfer adhesive, the PVDF piezopolymer thin film 330 is        wrapped around the circumference of the mandrel 240 a minimum of        a fraction of one single wrap, a single wrap, a non-integral        number of wraps, or a plurality of wraps depending on the length        of the piezoelectric acoustic film 330. While a single wrap        minimum is specified, it is desirable to create a complex        pattern of both filled and non filled transfer adhesive to        create a fractal sampling pattern for both the acoustic sensor        and the turbulent boundary sensor.    -   Electrical connection is made to the piezoelectric film by        crimps that puncture the piezoelectric film and provide a        conductive path to which wires are then attached to transmit the        desired signal which is a common practice in terminating        piezopolymer films.        Method of Manufacture

Still referring to FIG. 5, an example of method of manufacture isdescribed.

To make the invention, a rigid mandrel or substrate 210 is fabricated toproduce a desired form factor for the final embodiment as a seismicstreamer or sensor array 120. The substrate 210 or rigid mandrel is overmolded to place the required features onto the surface of the rigidmandrel to allow for the mounting and isolation of the two discreetsensors, such that the two sensors occupy the same space and are deemedco-located. The two sensors are optionally the motion sensor 200 andacoustic sensor 300. The motion sensor 200 optionally uses a uniqueliquid metal 232 that remains liquid within the operating temperaturerange, is conductive, and forms the inner electrode and mass of themotion sensor 200. The motion sensor 200 is immune to acoustic energy bythe placement of a rigid tube 240 that surrounds the motion sensor 200and prevents sound from accessing the volume where the motion sensorresides. The rigid tube 240 forms the substrate or base for the acousticsensor 300. The acoustic sensor 300 is formed around the outer substratewith a flexible microsphere loaded adhesive resident beneath and betweenthe film element and the rigid substrate. The film can be continuous orcan be comprised of discreet patterns of electrodes deposited onto thesurface of the polymer film to accomplish the desired responsecharacteristics.

Dual Element Sensors

A number of dual element sensors are electrically wired either in seriesor in parallel to form the desired group or aperture characteristics.Acoustic sensors are wired together providing one signal output and theacceleration sensors are wired together to provide a single signaloutput of acceleration. The embodiment of the group or aperture isoptionally a set of elements spaced as close to one another as ismechanically practical preserving the ability to bend the aperturearound a winch or sheave without damage while optimizing rejection ofmechanical energy propagating along the length of the cable. The wiredgroup is then loaded onto the core cable in the desired location bythreading the core cable through the inner diameter of the combinedsensor and electrically terminating to the core cable through a singleopening in the core cable jacket.

The group of sensors is placed in the group mold which fixes thelocation of the individual sensors within the group and along the lengthof the entire cable; the wires interconnecting the individual elementswithin the group are wrapped in two directions about the core cablebetween the discreet locations within the group. The group is molded tothe cable sealing the entrance of the wires into the core cable jacketeliminating potential leakage paths and centering the elements about thecable. Microsphere loaded solid flexible elastomer flotation is thenmolded over the entire cable length and over the individual groupshaving previously been mounted along the entire cable length.

The location of the motion sensor is optionally either beneath theacoustic sensor or adjacent to the acoustic sensor residing on the samerigid substrate. This allows for a reduced diameter of the entireembodiment as required. The spacing within the group between thediscreet elements of the group is optionally varied depending on thedesired response of the group with some elements spaced at one interval,some at another to tailor the response of the motion sensor to rejectundesirable energy propagating within the streamer assembly essentiallytuning the aperture to respond only to the desired verticallypropagating signal.

The dual sensor within a seismic streamer operates with two objectives,reduction of noise due to flow and the recovery of bandwidth in theacoustic domain that is lost as a result of the energy that ispropagating from the earth below, reflecting back from the sea surfaceand air interface, inverting and propagating down to the acousticreceivers in the streamer, thus interfering with the desired upwardpropagating signals causing a loss of signal within a bandwidthdetermined by the depth of tow relative to the reflected surface. Use ofboth an acoustic sensor and a motion sensor allows in post processing ofthe seismic data, the use of the inherent directional characteristics ofmotion to be convolved with the inherent characteristic lack ofdirection in acoustic signals to remove the downward propagating energyfrom the desired signals, thus recovering the lost energy and improvingthe resolution of the seismic data. This system provides that the motionand acoustic response from the discreet sensors result from the sameexcitation due to the co-location of the acoustic and motion sensors,allowing for improved processing results. The noise due to flow isreduced by placing a single continuous element where a portion of theelement is bonded to the substrate using a flexible microsphere loadedadhesive, which creates the acoustic sensing portion of the element. Theremaining surface of the element is coated with a non-sphere filledadhesive that bonds the polymer film directly to the surface of therigid substrate, thus preventing its changing length due to acousticenergy and an associated change in the circumference of the microspheresresiding beneath the film. The portion of the film with no microspheresresponds with only one axis of deformation, that being the thicknessaxis, to the force created by the turbulence present at the surface ofthe flotation material which in the case of the area where themicrospheres reside is unbounded and thus responds to the pressure. Theforce manifests itself out of phase with the pressure and thus thesignal generated in a contiguous piece of PVDF thin film causes the twosignals due to turbulent boundary layer flow noise to cancel, thusmitigating the overall response to this type of undesirable energy.

The use of these two distinct outputs from the differing sensors allowsdata processing for the recovery of lost energy due to the reflectionsfrom above at the air water interface. In one embodiment, the currentsystem places both the acoustic sensor 300 and motion sensor 200 in thesame physical space, thus minimizing any differences in response due totheir different location. The system also provides for a uni-axialaccelerometer that substantially senses only vertical motion or onlyvertical motion and does so with no complex mechanical parts or gimbalsand resides interior to the acoustic sensor. Co-locating the sensorsresults in a linear transfer function between the two sensors andsimplifies and improves post processing. The dual output sensor usesacceleration so that proper phase is maintained between the acousticresponse and the acceleration response.

The system uses a novel acceleration sensor to enable the co-locationand uni-axial sensing of particle motion in the water column with thesimultaneous sensing of dynamic pressure or sound with a novel thin filmpolymer piezoelectric acoustic sensor with the ability to mitigateunwanted noise due to turbulent boundary layer excitation. The systemuses a novel method of co-locating an acceleration sensor with thisnovel acoustic sensor.

The invention describes a novel acoustic sensor that uses flexible microballoons embedded within an adhesive attached to a piezopolymer elementallowing for deformation in response to dynamic acoustic pressure whilepreserving static pressure response and eliminating destructivedeformation of the polymer film sensor.

In varying embodiments, the sensor 124 comprises any of:

-   -   a thin film piezopolymer acoustic sensor incorporating a        flexible microsphere loaded transfer adhesive as the        compressible gas chamber providing high sensitivity and immunity        to overburden pressure;    -   a seismic streamer for marine seismic surveys embodying a thin        film piezopolymer acoustic sensor incorporating a unique        flexible microsphere loaded transfer adhesive as the        compressible gas chamber providing high sensitivity and immunity        to overburden pressure;    -   a thin film piezopolymer acoustic sensor incorporating a        flexible microsphere loaded transfer adhesive as the        compressible gas chamber providing high sensitivity and immunity        to overburden pressure combined with zones of non-microsphere        loaded transfer adhesive to act as sensors of the turbulent        boundary layer whose combined output provides for passive        cancelling of noise due to turbulent boundary layer flow;    -   a seismic streamer for marine seismic surveys embodying a thin        film piezo polymer acoustic sensor incorporating a unique        flexible micro-sphere loaded transfer adhesive as the        compressible gas chamber providing high sensitivity and immunity        to overburden pressure combined with zones of non-microsphere        loaded transfer adhesive to act as sensors of the turbulent        boundary layer whose combined output provides for passive        cancelling of noise due to turbulent boundary layer flow;    -   a monolithic sensor or multiple sensors housed in a single        housing, such as a rigid housing, dual output, flow noise        cancelling acoustic and liquid metal uniaxial motion sensor        embodied in a flexible elastomer, such as a syntactic elastomer,        based solid seismic streamer for marine seismic surveys;    -   a seismic streamer for marine seismic surveys embodying a thin        film piezo polymer acoustic sensor incorporating a flexible        microsphere loaded transfer adhesive as the compressible gas        chamber providing high sensitivity and near immunity to        overburden pressure combined with zones of non-microsphere        loaded transfer adhesive to act as sensors of the turbulent        boundary layer whose combined output provides for passive        cancelling of noise due to turbulent boundary layer flow;    -   a monolithic dual output, acoustic and motion sensor co-located        within a single discreet housing;    -   a monolithic dual output, acoustic sensor and motion sensor        utilizing an acoustic sensor employing a flexible piezopolymer        film, such as a syntactic backed piezopolymer film embodiment;    -   a monolithic dual output, acoustic and motion sensor utilizing a        liquid metal electrode arrangement, which uses gravity to place        the fluid mass and electrode in such a manner as to allow for        sensing only vertical motion and rejecting undesirable motion;    -   a monolithic dual output, acoustic and acceleration sensor        utilizing a novel pressure isolation method to prevent acoustic        response in the motion sensor response;    -   a seismic streamer for marine seismic surveys embodying a thin        film piezo polymer acoustic sensor incorporating a flexible        microsphere loaded transfer adhesive as the compressible gas        chamber providing high sensitivity and immunity to overburden        pressure combined with zones of non-microsphere loaded transfer        adhesive to act as sensors of the turbulent boundary layer whose        combined output provides for passive cancelling of noise due to        turbulent boundary layer flow combined with a novel monolithic        dual output, acoustic and motion sensor utilizing a novel liquid        metal electrode arrangement which uses gravity to place the        fluid mass and electrode in such a manner as to allow for        sensing only vertical motion and rejecting undesirable motion;    -   a monolithic dual output, acoustic and motion sensor embodied        within a flexible syntactic seismic streamer in groups that are        nested in complex spacing arrangements to enhance rejection of        undesirable signals; and    -   a monolithic dual output, acoustic and motion sensor embodied        within a flexible syntactic seismic streamer allowing for the        core electro-mechanical cable to reside within the diameter of        the sensor embodiment.

Still yet another embodiment includes any combination and/or permutationof any of the sensor elements described herein.

The particular implementations shown and described are illustrative ofthe invention and its best mode and are not intended to otherwise limitthe scope of the present invention in any way. Indeed, for the sake ofbrevity, conventional manufacturing, connection, preparation, and otherfunctional aspects of the system may not be described in detail.Furthermore, the connecting lines shown in the various figures areintended to represent exemplary functional relationships and/or physicalcouplings between the various elements. Many alternative or additionalfunctional relationships or physical connections may be present in apractical system.

In the foregoing description, the invention has been described withreference to specific exemplary embodiments; however, it will beappreciated that various modifications and changes may be made withoutdeparting from the scope of the present invention as set forth herein.The description and figures are to be regarded in an illustrativemanner, rather than a restrictive one and all such modifications areintended to be included within the scope of the present invention.Accordingly, the scope of the invention should be determined by thegeneric embodiments described herein and their legal equivalents ratherthan by merely the specific examples described above. For example, thesteps recited in any method or process embodiment may be executed in anyorder and are not limited to the explicit order presented in thespecific examples. Additionally, the components and/or elements recitedin any apparatus embodiment may be assembled or otherwise operationallyconfigured in a variety of permutations to produce substantially thesame result as the present invention and are accordingly not limited tothe specific configuration recited in the specific examples.

Benefits, other advantages and solutions to problems have been describedabove with regard to particular embodiments; however, any benefit,advantage, solution to problems or any element that may cause anyparticular benefit, advantage or solution to occur or to become morepronounced are not to be construed as critical, required or essentialfeatures or components.

As used herein, the terms “comprises”, “comprising”, or any variationthereof, are intended to reference a non-exclusive inclusion, such thata process, method, article, composition or apparatus that comprises alist of elements does not include only those elements recited, but mayalso include other elements not expressly listed or inherent to suchprocess, method, article, composition or apparatus. Other combinationsand/or modifications of the above-described structures, arrangements,applications, proportions, elements, materials or components used in thepractice of the present invention, in addition to those not specificallyrecited, may be varied or otherwise particularly adapted to specificenvironments, manufacturing specifications, design parameters or otheroperating requirements without departing from the general principles ofthe same.

Although the invention has been described herein with reference tocertain preferred embodiments, one skilled in the art will readilyappreciate that other applications may be substituted for those setforth herein without departing from the spirit and scope of the presentinvention. Accordingly, the invention should only be limited by theClaims included below.

The invention claimed is:
 1. A method for collecting seismic data, themethod comprising: towing a seismic streamer through a marine body abovea marine body floor and below a marine body surface of the marine body,wherein the seismic streamer further comprises a plurality of sensorsand a streamer cable coupled to the sensors, and wherein at least one ofthe sensors further comprises an acoustic-motion sensor that has anacoustic sensitivity to acoustic energy in the marine body and avertical sensitivity to gravitationally vertical acceleration of theacoustic-motion sensor; generating a shock wave in the marine bodywithin an acoustic range of the seismic streamer, wherein, responsive tothe shock wave, a first seismic wave is reflected from the marine bodyfloor and a second seismic wave is reflected from strata layers belowthe marine body floor, wherein the first seismic wave reflects off themarine body surface to generate a third seismic wave that propagatesdownward from the marine body surface towards the streamer cable, andwherein the third seismic wave interferes with the first seismic wave atthe streamer cable; detecting the first seismic wave and the secondseismic wave using the acoustic-motion sensor to generate an acousticsignal responsive to the acoustic sensitivity; detecting the thirdseismic wave using the acoustic-motion sensor to generate a verticalacceleration signal responsive to the vertical sensitivity; combiningthe acoustic signal and the vertical acceleration signal to improve asignal-to-noise ratio of the acoustic signal responsive to the acousticsensitivity; and cancelling noise in the acoustic signal from turbulentflow around the seismic streamer using a combined output of a firstportion and a second portion of an acoustic piezoelectric film enablingthe acoustic sensitivity, wherein the first portion is attached using afirst adhesive loaded with flexible microspheres to enable forcesensitivity of the first portion to deformation from the turbulent flow,and wherein the second portion is not attached using the flexiblemicrospheres.
 2. The method of claim 1, wherein the acoustic-motionsensor further comprises: a tube longitudinally enclosing the streamercable and having a tube radius; the acoustic piezopolymer film; thefirst portion of the acoustic piezopolymer film flexibly bonded at afirst longitudinal location to the tube using the first adhesive loadedwith flexible microspheres, wherein the first adhesive additionallyenables force sensitivity of the first portion to deformation fromturbulent flow at a boundary layer between the seismic streamer and themarine body; and the second portion of the acoustic piezopolymer filmrigidly bonded at a second longitudinal location to the tube using asecond adhesive, the second adhesive not being loaded with the flexiblemicrospheres and not enabling the force sensitivity to deformation,wherein the first longitudinal location and the second longitudinallocation are mutually exclusive locations.
 3. The method of claim 1,wherein detecting the third seismic wave using the acoustic-motionsensor to generate the vertical acceleration signal responsive to thevertical sensitivity further comprises: generating the verticalacceleration signal using a conductive fluid in contact with a motionpiezopolymer film different from the acoustic piezopolymer film.
 4. Themethod of claim 3, wherein generating the vertical acceleration signalfurther comprises: receiving the vertical acceleration signal from themotion piezopolymer film in contact with the conductive fluid freelyflowing circumferentially in an enclosed chamber about the tube, whereinthe conductive fluid contacts the motion piezopolymer film at onesurface and an electrode contacts the motion piezopolymer film at anopposing surface.
 5. The method of claim 4, wherein the enclosed chamberhas a first radius about the tube that is greater than the tube radius.6. The method of claim 5, wherein the first longitudinal locationcorresponds longitudinally to a third longitudinal location of themotion piezoelectric film and the enclosed chamber on the tube.
 7. Themethod of claim 6, wherein the first longitudinal location, the secondlongitudinal location, and the third longitudinal location are adjacentalong the tube.
 8. The method of claim 6, wherein the acoustic-motionsensor further comprises an outer mandrel surrounding and cylindricallyconcentric to the tube, wherein the acoustic piezopolymer film is bondedto the outer mandrel instead of the tube, and wherein a second radius ofthe outer mandrel is greater than the first radius.
 9. The method ofclaim 8, wherein the first longitudinal location and the secondlongitudinal location are adjacent along the outer mandrel, and thethird longitudinal location on the tube is longitudinally equivalent tothe first longitudinal location.
 10. The method of claim 1, whereincombining the acoustic signal and the vertical acceleration signalfurther comprises: combining the acoustic signal and the verticalacceleration signal using a linear transfer function.
 11. The method ofclaim 1, wherein cancelling noise in the acoustic signal from turbulentflow around the seismic streamer further comprises: increasing asignal-to-noise ratio for the second seismic wave in the acousticsignal, wherein the third seismic wave interferes with the first seismicwave.
 12. A method for collecting seismic data, the method comprising:detecting, at an acoustic-motion sensor located in a marine body, afirst seismic wave and a second seismic wave to generate an acousticsignal, wherein the first seismic wave and the second seismic wave arereflected from a marine body floor of the marine body upwards towardsthe acoustic-motion sensor, and wherein the first seismic wave isreflected from the marine body floor and the second seismic wave isreflected from strata layers below the marine body floor; detecting athird seismic wave using the acoustic-motion sensor to generate avertical acceleration signal, wherein the third seismic wave is thefirst seismic wave reflected from a marine body surface of the marinebody downwards towards the acoustic-motion sensor; combining theacoustic signal and the vertical acceleration signal to improve asignal-to-noise ratio of the acoustic signal; and cancelling noise inthe acoustic signal from turbulent flow around the acoustic-motionsensor using a combined output of a first portion and a second portionof an acoustic piezoelectric film, wherein the first portion is attachedusing a first adhesive loaded with flexible microspheres to enable forcesensitivity of the first portion to deformation from the turbulent flow,and wherein the second portion is not attached using the flexiblemicrospheres.
 13. The method of claim 12, wherein the acoustic-motionsensor further comprises: a tube longitudinally enclosing a streamercable coupled to the acoustic-motion sensor, the tube having a tuberadius; the acoustic piezopolymer film; the first portion of theacoustic piezopolymer film flexibly bonded at a first longitudinallocation to the tube using the first adhesive loaded with flexiblemicrospheres, wherein the first adhesive additionally enables forcesensitivity of the first portion to deformation from turbulent flow at aboundary layer between the seismic streamer and the marine body; and thesecond portion of the acoustic piezopolymer film rigidly bonded at asecond longitudinal location to the tube using a second adhesive, thesecond adhesive not being loaded with the flexible microspheres and notenabling the force sensitivity to deformation, wherein the firstlongitudinal location and the second longitudinal location are mutuallyexclusive locations.
 14. The method of claim 12, wherein detecting thethird seismic wave using the acoustic-motion sensor to generate thevertical acceleration signal further comprises: generating the verticalacceleration signal using a conductive fluid in contact with a motionpiezopolymer film different from the acoustic piezopolymer film.
 15. Themethod of claim 14, wherein generating the vertical acceleration signalfurther comprises: receiving the vertical acceleration signal from themotion piezopolymer film in contact with the conductive fluid freelyflowing circumferentially in an enclosed chamber about the tube, whereinthe conductive fluid contacts the motion piezopolymer film at onesurface and an electrode contacts the motion piezopolymer film at anopposing surface.
 16. The method of claim 15, wherein the enclosedchamber has a first radius about the tube that is greater than the tuberadius.
 17. The method of claim 16, wherein the first longitudinallocation corresponds longitudinally to a third longitudinal location ofthe motion piezoelectric film and the enclosed chamber on the tube. 18.The method of claim 17, wherein the first longitudinal location, thesecond longitudinal location, and the third longitudinal location areadjacent along the tube.
 19. The method of claim 17, wherein theacoustic-motion sensor further comprises an outer mandrel surroundingand cylindrically concentric to the tube, wherein the acousticpiezopolymer film is bonded to the outer mandrel instead of the tube,and wherein a second radius of the outer mandrel is greater than thefirst radius.
 20. The method of claim 19, wherein the first longitudinallocation and the second longitudinal location are adjacent along theouter mandrel, and the third longitudinal location on the tube islongitudinally equivalent to the first longitudinal location.
 21. Themethod of claim 12, wherein combining the acoustic signal and thevertical acceleration signal further comprises: combining the acousticsignal and the vertical acceleration signal using a linear transferfunction.
 22. The method of claim 12, wherein cancelling noise in theacoustic signal from turbulent flow around the acoustic-motion sensorfurther comprises: increasing a signal-to-noise ratio for the secondseismic wave in the acoustic signal, wherein the third seismic waveinterferes with the first seismic wave.